Integrated Genomics Identifies Five Medulloblastoma Subtypes with Distinct Genetic Profiles, Pathway Signatures and Clinicopathological Features

BACKGROUND: Medulloblastoma is the most common malignant brain tumor in children. Despite recent improvements in cure rates, prediction of disease outcome remains a major challenge and survivors suffer from serious therapy-related side-effects. Recent data showed that patients with WNT-activated tumors have a favorable prognosis, suggesting that these patients could be treated less intensively, thereby reducing the side-effects. This illustrates the potential benefits of a robust classification of medulloblastoma patients and a detailed knowledge of associated biological mechanisms. METHODS AND FINDINGS: To get a better insight into the molecular biology of medulloblastoma we established mRNA expression profiles of 62 medulloblastomas and analyzed 52 of them also by comparative genomic hybridization (CGH) arrays. Five molecular subtypes were identified, characterized by WNT signaling (A; 9 cases), SHH signaling (B; 15 cases), expression of neuronal differentiation genes (C and D; 16 and 11 cases, respectively) or photoreceptor genes (D and E; both 11 cases). Mutations in beta-catenin were identified in all 9 type A tumors, but not in any other tumor. PTCH1 mutations were exclusively identified in type B tumors. CGH analysis identified several fully or partly subtype-specific chromosomal aberrations. Monosomy of chromosome 6 occurred only in type A tumors, loss of 9q mostly occurred in type B tumors, whereas chromosome 17 aberrations, most common in medulloblastoma, were strongly associated with type C or D tumors. Loss of the inactivated X-chromosome was highly specific for female cases of type C, D and E tumors. Gene expression levels faithfully reflected the chromosomal copy number changes. Clinicopathological features significantly different between the 5 subtypes included metastatic disease and age at diagnosis and histology. Metastatic disease at diagnosis was significantly associated with subtypes C and D and most strongly with subtype E. Patients below 3 yrs of age had type B, D, or E tumors. Type B included most desmoplastic cases. We validated and confirmed the molecular subtypes and their associated clinicopathological features with expression data from a second independent series of 46 medulloblastomas. CONCLUSIONS: The new medulloblastoma classification presented in this study will greatly enhance the understanding of this heterogeneous disease. It will enable a better selection and evaluation of patients in clinical trials, and it will support the development of new molecular targeted therapies. Ultimately, our results may lead to more individualized therapies with improved cure rates and a better quality of life

Impaired DNA damage response signaling by FUS-NLS mutations leads to neurodegeneration and FUS aggregate formation

Amyotrophic lateral sclerosis (ALS) is the most frequent motor neuron disease. Cytoplasmic fused in sarcoma (FUS) aggregates are pathological hallmarks of FUS-ALS. Proper shuttling between the nucleus and cytoplasm is essential for physiological cell function. However, the initial event in the pathophysiology of FUS-ALS remains enigmatic. Using human induced pluripotent stem cell (hiPSCs)-derived motor neurons (MNs), we show that impairment of poly(ADP-ribose) polymerase (PARP)-dependent DNA damage response (DDR) signaling due to mutations in the FUS nuclear localization sequence (NLS) induces additional cytoplasmic FUS mislocalization which in turn results in neurodegeneration and FUS aggregate formation. Our work suggests that a key pathophysiologic event in ALS is upstream of aggregate formation. Targeting DDR signaling could lead to novel therapeutic routes for ameliorating ALS

Hyperlactataemia in HIV-infected patients: the role of NRTI-treatment

BACKGROUND: Long-term treatment with nucleoside reverse transcriptase inhibitors (NRTIs) can induce mitochondrial dysfunction, most severely represented by lactic acidosis. Diagnostic tests for mitochondrial dysfunction are lacking, although persistently elevated serum lactate might be a surrogate marker. OBJECTIVES: To determine the occurrence of hyperlactataemia in HIV-infected patients on NRTI-treatment and to evaluate the possible risk factors. METHODS: Cross-sectional analysis of lactic-acid levels in asymptomatic HIV-infected patients. Hyperlactactaemia was considered mild if between 2.0-5 mmol/l, serious if >5 mmol/l and lactic acidosis was defined as lactic acid levels >5 mmol/l with bicarbonate <20 mmol/l. Possible risk factors, such as current and preceding NRTI-treatment as well as treatment with non-nucleoside reverse transcriptase inhibitors or protease inhibitors and concurrent liver disease, were analysed. RESULTS: Two hundred and twenty three asymptomatic HIV-infected patients were studied, including 174 patients (78%) on NRTI treatment, 12 patients (5%) treated without NRTIs and 37 patients (17%) not treated. Mild hyperlactataemia was found in 42 patients (19%), from whom 38/42 (90%) were NRTI-treated and the remaining patients (4/42, 10%) received no treatment (chi2, P <0.05). The significant risk factors for hyperlactataemia in the univariate analysis were NRTI-treatment as a group (P=0.03) and elevated ALT (P=0.008). In multivariate analysis NRTI use (P=0.05) and ALT level (P=0.03) remained a significant determinant of hyperlactataemia. Among the different individual NRTIs, a stavudine-containing (P=0.004) and a zalcitabine-containing (P=0.07) regimen were most notably associated with the development of hyperlactataemia, whereas for the combinations of NRTIs, such association was only found for stavudine/lamivudine (P=0.05). CONCLUSIONS: A correlation between hyperlactataemia and NRTI treatment was found, but the value of routine lactate measurement for individual treatment monitoring remains uncertai

Biomarkers of Nutrition for Development (BOND) - Zinc Review

Zinc is required for multiple metabolic processes as a structural, regulatory, or catalytic ion. Cellular, tissue, and whole body zinc homeostasis is tightly controlled to sustain metabolic functions over a wide range of zinc intakes, making it difficult to assess zinc insufficiency or excess. The BOND Zinc Expert Panel recommends three measurements for estimating zinc status: dietary zinc intake, plasma zinc concentration (PZC), and the height-for-age of growing infants and children. The amount of dietary zinc potentially available for absorption, which requires an estimate of dietary zinc and phytate, can be used to identify individuals and populations at risk of zinc deficiency. PZCs respond to severe dietary zinc restriction and to zinc supplementation; they also change with shifts in whole body zinc balance and clinical signs of zinc deficiency. PZC cutoffs are available to identify individuals and populations at risk of zinc deficiency. However, there are limitations in using PZC to assess zinc status. PZC respondsless to additional zinc provided in food than to a supplement administered between meals, there is considerable inter-individual variability in PZC with changes in dietary zinc, and PZC is influenced by recent meal consumption, the time of day, inflammation, and certain drugs and hormones. Insufficient data are available on hair, urinary, nail, and blood cell zinc responses to changes in dietary zinc to recommend these biomarkers for assessing zinc status. Of the potential functional indicators of zinc, growth is the only one recommended. Because pharmacologic zinc doses are unlikely to enhance growth, a growth response to supplemental zinc is interpreted as indicating pre-existing zinc deficiency. Other functional indicators reviewed, but not recommended for assessing zinc nutrition in clinical or field settings because of insufficient information, are the activity or amounts of zinc-dependent enzymes and proteins, and biomarkers of oxidative stress, inflammation, or DNA damage